A shortcoming of global positioning system (GPS) based navigation and steering control systems used in agricultural ground vehicles is that the global positioning system receiver of such systems can only determine the position of the global positioning system antenna. On most ground vehicles, the mounting location for the global positioning system antenna is constrained by the requirement that a clear view of the sky, and thus the global positioning system satellites, be provided to the antenna.
As a consequence of this limitation, current global positioning system based navigation and steering control systems take only ground vehicle receiver position into account when regulating ground vehicle position. However, implements towed by the ground vehicle will tend to drift to the inside of a constant radius turn. This drift is especially problematic to operators when making headland turns. During a headland turn, the towed implement will drift to the inside of the turn. When the operator lowers the implement after the turn, a significant initial lateral error can be exhibited. To compensate for this error, a skilled operator will often intentionally overshoot the desired track with the ground vehicle in order to pull the towed implement more quickly onto the line along the track. However, less skilled operators may fail to make this compensation, resulting in uneven tillage or application of seed and/or chemicals (e.g., fertilizer, herbicide, and the like) particularly near the periphery of a field.
Consequently, it would be advantageous to provide a global positioning system (GPS) based navigation and steering control system for agricultural ground vehicles such as tractors, or the like, which employs a system and method for calculating instantaneous placement corrections to achieve desired towed implement placement on curved paths for both headland turns and in field operations.